diff --git a/icu4c/source/common/locid.cpp b/icu4c/source/common/locid.cpp
index 35465a201ac..33b7cc75fe5 100644
--- a/icu4c/source/common/locid.cpp
+++ b/icu4c/source/common/locid.cpp
@@ -510,7 +510,7 @@ Locale::operator==( const   Locale& other) const
     return (uprv_strcmp(other.fullName, fullName) == 0);
 }
 
-#define ISASCIIALPHA(c) ((c) >= 'a' && (c) <= 'z' || (c) >= 'A' && (c) <= 'Z')
+#define ISASCIIALPHA(c) (((c) >= 'a' && (c) <= 'z' || (c) >= 'A' && (c) <= 'Z'))
 
 /*This function initializes a Locale from a C locale ID*/
 Locale& Locale::init(const char* localeID, UBool canonicalize)
diff --git a/icu4c/source/common/uloc.cpp b/icu4c/source/common/uloc.cpp
index 8b6d9261e62..3fc68d1f39b 100644
--- a/icu4c/source/common/uloc.cpp
+++ b/icu4c/source/common/uloc.cpp
@@ -1248,7 +1248,7 @@ ulocimp_getLanguage(const char *localeID,
     return i;
 }
 
-#define ISASCIIALPHA(c) ((c) >= 'a' && (c) <= 'z' || (c) >= 'A' && (c) <= 'Z')
+#define ISASCIIALPHA(c) (((c) >= 'a' && (c) <= 'z' || (c) >= 'A' && (c) <= 'Z'))
 
 U_CFUNC int32_t
 ulocimp_getScript(const char *localeID,